Sunglasses change colour by your command

I love my prescription glasses which change tint so delicately that I often forget that the sun even exists, but those could seem like monochrome compared to new sunglasses on the horizon that change colour at your whim. They switch even faster than conventional fast-tinting lenses and can go to any shade of blue. Also, it uses an organic compound inside the lens, which, once zapped to change, stays that way without any sustaining power. “You can adjust the variation of darkness and control the transparency of your lens,” said Minoru Taya, professor of mechanical engineering at the University of Washington. Researchers are working on red and green, the combination of which, with the existing blue, would allow any colour at all. Not only would this make great sunglasses, it would open up new possibilities for energy efficient windows and tinted windshields. [GT]